The incident occurred about 200 yards offshore in Anaeho'omalu Bay.
The injured man was able to make it to a catamaran docked at the bay, where the crew took him in and helped control the bleeding to his upper and lower extremities.
A jet ski then brought the man to the beach, where Hawaii County Fire Department personnel were waiting.
The man was transported to North Hawaii Hospital.
It is unclear what type of shark it was that bit the man, or its size.